added line to add db name to the env file

Jenkinsfile

@@ -5,6 +5,7 @@ pipeline {
     stage('Init') {
       steps {
         sh 'rbenv local 3.2.2'
+        sh 'echo "ENV[\"DB_NAME\"] ||= \"url_shortener.db\" >> .env.rb'
       }
     }
   }